Sound operated relay system



Jail. 6, 1948,- H0. HAYES ETAL SOUND OPERATED RELAY SYSTEM Filed Nov. 28. 1941 mvavrons Hazvey GHQ/95 liorme M Trent nrr omvsr:

Patented Jan. 6, 1948 SOUND OPERATED RELAY SYSTEM Harvey C. Hayes, Washington, D. 0., and

Horace M. Trent, Alexandria, Va.

Application November, 28, 1941, Serial No. 420,852 4 Claims. (01.175-320) (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) This invention relates to a relay system which is responsive to sound waves or to vibratory impulses of a similar nature.

The system comprises a trigger circuit contaming a relay coil and an impulse operated switch. The circuit is so arranged as to remain ineffective to energize the relay coil to its operating level as long as the impulse operated switch remains closed. Reception of an impulse by the switch causes it to open andcauses the circuit to energize the relay coil to operation. After a predetermined period of time the circuit returns to its unexcited state unless the switch is open at'the time. The switch is so constructed as to operate particularly Well upon the reception of random noises or impulses of this nature. Among the various objects of this invention are:

To provide a sound operated means for varying the energization of a work circuit.

To provide means operated -by the reception of random vibratory impulses for varying the energization of a work circuit.

To provide a relay trigger circuit containing a switch responsive to the reception of sound waves or similar impulse to energize the circuit.

To provide an impulse operated switch capable of being opened by the reception of sound waves or similar impulses.

To provide an impulse operated switch capable of being set into a, chattering condition by the reception of random impulses To'provide an impulse actuated relay circuit capable of exercising on a work circuit a. variety of sequential control actions.

Other objectswill become apparent from a consideration of the following description when taken together with the accompanying drawings in which:

Fig. 1 is a side ele'vational view partly in cross section of the impulse operated switch forming a part of the invention;

Fig. 2 is a side elevational view of the switch shown in Fig. 1 taken along the section indicated by line 2-2 in Fig. 1, and having portions broken away, and

Fig. 3 is a, schematic diagram of a trigger circuit forming a part of the invention.-

The impulse operated switch S illustrated in Figs. 1 and 2 comprises a casing having thick cylindrical side walls I and a heavy rigid end wall 2, the opposite end of the casing beingclosed by a sound or impulse sensitive diaphragm 3. Mounted on the vibrating diaphragm 3 is a post 4 which is sectionalized so that its tip 5 is separated from its main portion by a connecting means 6 formed of electrical insulation material. The tip of the post serves as one contact of the switch and may be made of a polished non-corrodible metal suitable for this purpose. Rigidly secured to heavyend wall 2 of the housing are a pair of depending arms I in the lower ends of which is journalled a shaft 8 carrying a spring actuated balance wheel 9 of the type normally found in clock mechanisms. Instead of the wheel 9 a balanced rod could be used. The spring Ill is shown as a spiral spring having one end secured to an arm ll forming a rigid part of the supporting'means of the shaft 8 and having its other end secured to the shaft 8. The natural period of the balance wheel may be changed by varying the length. of the spring. Obviously other forms of springs may be employed. A polished metal peg l2 extends from the circumference of the balance wheel and forms the other contact for the switch. The tip 5 of the post 4 has secured to it a conductor l3, the other end of which is secured to a binding post l4 which passes through and is electrically insulated from the end wall 2 of the housing. The balance wheel assembly including the arms! forms a conducting circuit from the peg l2 to a binding post l5 which likewise passes through and is insulated from the end wall 2. The wheel 9 is carefully balanced and its sensitivity may be enhanced by the employment of jeweled hearings to support the shaft 8. Conventional means is provided for adjusting the tightness of the bearings.

The switch as described above is sensitive to the reception of sound waves or similar pulses by the diaphragm 3. Upon the reception of such waves the contact I2, which is normally lightly pressed against the contact 5 by means of the spring Ill,

transmits the received impulse to the balance wheel. The wheel is rotated thereby and the assasse 3 the contact I2 to its contacting position with respect to contact 5. The switch will then preferably remain closed unless the diaphragm 3 is being vibrated. The continued reception of sound waves causes a chattering condition to be set up inthe switch.

While the switch will respond effectively to sinusoidal excitation it works particularly well upon the reception of random noises which contain a good many pulses of high intensity. One of the best fields of use of the invention lies in the detection of random impulses and their utilization to control the operation of various mechanisms.

The switching means forms a part of the trigger circuit shown in Fig. 3, its position in the circuit being indicated by the binding posts It and it. A pair of cold-cathode tubes V1 and V2 are contained in the circuit. The impulse responsive switch 8 is connected across the binding posts I d and I5 which puts it in series with resistance R2, time constant circuit R1C1, batteryB1 relay l8 and resistance R3. The R. 0. time constant circuit R1C1 is connected directly across the grid and plate of V1.

The plate and cathode of V: are connected by a circuit made up of resistance Rs in series with two parallel branches, one containing battery B1 and resistance Rs and the other containing the condenser C4. The cathodes of the two tubes are connected together through condenser C11. Biasing battery B2 is connected between the grid of V1 and the cathode of V1, a resistance R4 lying between the battery B1 and the grid. A blocking condenser C3 lies between the grid and cathode of V2. The p rpose of the circuit is to control the energization of the coil I 6 of a relay switch I? forming part of a work circuit diagrammatically illustrated at It.

Since in the normal unexcited condition of the relay circuit the switch S is in the closed position, it is essential that the battery drain across it be reduced to the minimum. The circuit shown in Fig. 3 accomplishes this result very effectively. With the switch S closed, a short circuit exists between the binding posts I l and i5. In this condition the current through the path comprising the positive terminal of B1, resistances R1 and R2, contacts l4 and I5 (closed), R3, element It and the negative terminal of B1, is the only one of appreciable size flowing in the circuit. The values of the resistances R1 and R2, can be made such that the drain across them compares favorably with that normally occurring during the shelf life or the battery. The above outlined path is the only path in the circuit not blocked by electronic tubes or condensers. Thus, if the condensers and tubes were perfect, there would be no possibility of current flow through other paths of the circuit. If good condensers are used their leakage current is negligible. The current through R1 and R2 is small because the total resistance in the circuit is preferably about 2,100,000 ohms, which gives a current of .000064 ampere.

The cold cathode tubes V1 and V2 are preferably of the 313C type and normally operate as follows:

The tube is non-conducting until the potential diflerence between grid and cathode exceeds 75 volts. Once the tube becomes conducting, the

grid loses control and conduction continues untiltwo conditions are satisfied simultaneously, (a) the potential difference between plate and cathode must be less than 75 volts, and (b) the po- 4 tential difference between grid and cathode must be less than 60 volts.

In the unexcited state with contacts I l-l8 closed, the following voltages appear on the elements or the tubes, with reference to the negative terminal of battery B1.

Since neither grid has a potential '15 volts great-- er than its corresponding cathode, both tubes remain non-conducting.

When the contacts ll-IS open due to a noise disturbance, C1 starts discharging through R1 so that the grid potential of V1 starts raising. In .0015 second the grid potential of V1 will reach 75 volts with respect to the cathode and the tube will become conducting. The current follows the path, positive terminal of B1, plate of V1, cathode of V1, R3, relay coil 5 to negative terminal of B1. This current operates the relay thus closing contact 11. When V1 is conducting, the voltages of the tube elements with reference to the negative terminal of B1 or as follows: plate 135 volts, cathode 60 volts, grid 120 volts if contacts I l-I5 are open, 60 volts if contacts i l-I5 are closed and V1 is still conducting.

At the instance V1 becomes conducting, the 60 volts between its cathode and negative terminal of B1 (drop across R3 and I6, V1 conducting) is 7 added to the grid circuit of V2.

If it were not for the presence of R4 and C3 the grid potential of V2 would become volts instantaneously and V2 would become conducting. The function of the elements R4 and Ca is to prevent the grid potential of V2 from exceeding 75 volts the instant V1 becomes conducting. They introduce a delay in the rise of potential of the grid of V1 so that some time elapses before V1 is rendered conducting. This delay is determined by the product R4 and Ca and may have values between /15 and 10 seconds with ease. The potential of the grid of V2 can rise only by charging the condenser C3. It is charged through the circuit, cathode of V1, 32, R4, C3, Re, B1. plate of V1 back to cathode of When C: has been charged sufllcie'ntly to make the grid potential of V2 75 volts with respect to its cathode, V2 becomes conducting. C4 is discharged through V2 and. Rs in approximately .005 second. C3 is discharged through the grid and cathode of V2. At the comp etion of these discharges, Vz becomes non-conducting. C4 is recharged through the circuit: B1, R5, and C1, and with V1 still conducting and contacts |4-.-l5 remaining open the cycle repeats itself so long as lfl-IE are open. Thus V2 and associated parts constitute a relaxation oscillator in which C4 and C3 are discharged at regular intervals.

Each time V2 becomes conducting, the potential of its cathode relative to the negative terminal of B1 suddenly jumps from 0 to 60 volts. This sudden jump in the cathode voltage of V: caused a corresponding instantaneous rise in the potential of the cathode of V1 since these two cathodes are connected through the condenser C2. This satisfies the conditions for the extinction of V1 and so it becomes momentarily non-conducting and V1 will remain non-conducting if this moment finds contacts l4-l5 closed, otherwise it becomes conducting again as soon as the cathode potential of V1 returns to its normal conducting value (60 volts). Upon closure of contacts l4l5 during a non-conducting period of V2, then the next discharge of C4 and Ca through V2 will render V1 permanently non-conducting. While V1 is non-conducting, the potential of the grid of'Vz cannot exceed 45 volts so that V: can never become conducting again until V1 is rendered conducting. The circuit now has returned to its normal state.

Many types of control actions are. possible with this invention. It the relay must remain in continuous operation while a noise persists, a slow opening relay must be used. This is necessary because there is always the probability that the switch S may make a contact at the same instant V2 fires in which case V1 becomes non-conducting for a very small fraction of a second. Allowance must also be made for the relay remaining closed after the noise has stopped for an interval-not exceeding the periodicity of the intermittent operation of V2. By varying both the periodicity of operation of V2 and the type of relay employed quite a large variation can be secured in the type of control established. The number of operations such a device might initiate from its relay contacts is without limit.

According to the provisions of the patent statutes, we have set forth the prinicipal mode of operation of our invention and have illustrated,

and described what we now consider to represent its best embodiments. However, we desire to have it understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically illustrated and described.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

We claim:

1. In an impulse actuated relay system a normally-closed compressional-wave operated switch, said switch being closed in its unexcited state, a trigger circuit, a relay coil, a source of electrical current for energizing said coil, a high resistance path forming a part of said circuit, said path including said source, said switch and said coll, a cold cathode tube having an anode, grid and cathode, an alternate low resistance path including said source and said coil and being shunted around said switch through said tube, an R. C. time-constant circuit comprising a resistance and condenser connected in multiple across the anode and grid of-said tube and in series in said high resistance circuit whereby the condenser remains charged during closure of said high resistance circuit to apply a blocking bias to said tube as long as said switch remains closed, the condenser of said R. C. circuit being discharged to remove in said path, said path including said source, said switch and said coil, acold cathode detector tube, an alternate low resistance path including said source and said coil being shunted around said switch through-said tube, an R. C. time-constant circuit comprising a resistance and condenser connected in multiple across the anode and grid of said tube and in series in said high resistance circuit whereby the condenser remains charged during closure of said high resistance circuit to apply a blocking bias to said tube as long as said switch remains closed, said condenser being discharged through said resistance to remove said blocking bias from said tube when said switch is opened by the reception of an impulse thereby, whereby said tube will be rendered conducting and the energization of said coil will be raised to an operating level, a relaxation oscillator in said trigger circuit, means for utilizing the flow of current through said alternate path to excite said oscillator, and means for causing each oscillation of said oscillator momentarily to render said detector tube non-conducting.

3. A relay system comprising a source of direct current, a cold cathode triode, a first limiting resistance and an electrically actuated relay all connected in series; the positive side of the current source being connected to the plate of the said triode, a normally-closed compressional-wave operated switch connecting the grid of the triode with the negative terminal of the source in series with said relay said first limiting resistance and a second limiting resistance, a time constant circuit comprising a resistance and capacity connected in multiple across the plate and grid of said triode to apply a blocking bias to the triode, a dropping resistance connecting the negative 7 terminal of the source through a coupling con said blocking bias from said tube when said switch is opened by the'reception of impulses thereby, whereby said tube will be rendered conducting and the energization of said coil will be raised to an operating-level and means rendered operative by the flow of current through said alternate path momentarily to render said tube non-conducting after a predetermined period of time.

2. In an impulse actuated relay system a nor-- mally-closed compression-wave operated switch,

said switch being closed in its unexcited state, a

denser to the cathod to effect a rise in potential of the cathode upon a flow of current through the dropping resistance, a storage condenser, a second cold cathode triode, said storage condenser connecting the negative terminal of said source with the plate of said second triode, the cathode of said second triode being connected to that side of the dropping resistance which connects to the coupling condenser, a grid condenser connected directly across the grid and cathode of the second triode, a second direct current source and a timing resistance connected in series between the cathode of the first triode and the grid of the second triode with the positive terminal of said source nearer said grid and the negative terminal nearer said cathode, and a charging resistance connecting the positive terminal of said first source to the plate of said first triode and therefore to that side of the storage condenser whic is connected to the said plate.

4. A relay system comprising a first source of unidirectional current, a cold cathode tube, a first limiting resistance and an electrically operated relay all connected in series, the positive side of the current source being connected to the plate of said tube, a normally-closed compressionalwave operated switch connecting the grid of the tube with the negative terminal of the source in series with said relay said first limiting resistance and a second limiting resistance, a time constant circuit comprising a resistance and a capacity connected" in multiple across the plate and grid of said tube wherebydisconnection of said grid from the said negative terminalwill permit the grid to rise in potential relative to the said negative terminal during discharge of the condenser and render the triode conducting, and means 7 intermittently raising the potential or said cathode relative to the negative terminal of said source controlled in the output circuit of the tube.

HARVEY c. HAYES. HORACE M. TRENT.

REFERENCES crmn The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Bergen Feb. 7, 1922 Number 8 Name Date Le Van et al July 12, 1932 Woodford Aug. 23, 1932 Praetorlus Oct. 1, 1935 Harris Feb. 16, 1937 Allen Mar. 30, 1936 Lindsay. June 29, 1937 Luhn Mar. 15, 1938 Berkey et a1. Nov. 12, 1940 Lamb Mar. 4, 1941 Rich Sept, 9, 1941 Gulliksen May 5, 1942 

